Communication methods are diversified from the wired communication to the wireless communication, transmitting the voice, the image, the video, the text message and the data file, which enables communication between people to become more convenient. The traditional voice communication is completely transited from an analog manner to a digital manner. The development of the digital technology makes the transmission of all information to a transmission process of bit zero and bit one. The emergence of Ethernet technology connects computers which work independently to form a local area network capable of sharing information resources. Furthermore, on the basis of the Ethernet, the Internet connects computers around the world together. The technologies such as the wireless local area network WLAN, the Bluetooth, the Zigbee liberate people from the bondage of wire harness. With the boost of mobile digital communication technology, people working, communicating and obtaining information in the mobile manner is common these days. With the improvement of the intelligent degree, the wireless communication technology is widely applied to various industries and is developed from connecting people to connecting anything.
The Internet of Things emerges as the times require, from smart home, smart transportation, smart workshop, smart warehouse to any intelligent application that can be imagined, the need of interconnection between things can be seen, wireless communication technology is being further developed to adapt to this change.
The wireless local area network WLAN is not suitable for object-to-object interconnection mainly because it is based on a star network topology architecture taking an AP as a center and based on a TCP/IP protocol which requires an IP address to be configured. The former factor leads to the inability of direct connection between devices, although WLAN also supports Mesh multi-hop network architecture, it still needs to connect into AP eventually. The complexity of the latter factor makes it impossible to complete without human participation, and the communication distance of AP is limited, It is difficult to manage the movement of mobile devices from one AP region to another AP region. Even for a fixed device, such as a simple application like transferring a file from a mobile phone to a tablet computer, the manual operation complexity is large. WiFi Direct technology developed by WiFi Alliance can realize point-to-point communication between two devices, but it still cannot solve the interconnection problem of automatic networking of multiple devices, especially mobile devices.
Compared with WLAN, Bluetooth has a narrow communication bandwidth, and mainly based on point-to-point topology architecture, it can form a very small number range of micro-networks Piconet, and then a plurality of Piconets are connected to form a Scatternet. Bluetooth has the advantages of being high in security and low in power consumption, and the developed Bluetooth Smart technology has the advantages that the power consumption is reduced to be lower, and the communication distance is longer. Bluetooth communication needs to be paired firstly, and is not suitable for random connection between objects.
From the perspective of network topology architecture, Zigbee ad hoc network functions and dynamic routing methods adopt multi-hop communication and can meet the requirement that device temporarily joins the network. It can adapt to a large number of device networking communications. However, it is based on a starting point of the establishment and management of a network, the maintenance of routing is relatively complex, and there is no reciprocity between devices.
Examining the existing wireless communication technology, there is single-hop communication based on point-to-point topology architecture or star-shaped architecture, or multi-hop communication similar to Zigbee. Some can enable communication between a plurality of devices, but the devices are not equal and the number of devices capable of being connected is also limited, it is difficult to add a new device, especially mobile devices which are hard to manage.
From the perspective of equality of all things, the communication network between objects should be a reciprocal network, wherein each device is in an equal position. The communication between devices is simple and direct, just like the communication between people, through inquiry and greeting. A device exchanges information with another device beyond its effective communication distance, by forwarding information through adjacent devices, each device can be either an initiator of a communication transaction or an accessed target or a forwarder in another communication transaction.